There have been a variety of electronic dictionaries published, such as the American Heritage Talking Dictionary, the Meriam Webster's Collegiate Dictionary and the Random House Unabridged Dictionary, which operate on full text searches with Boolean operators. These rely on a specific definition or a specific combination of words to access the word sought. Any deviation in the defining words entered from that of the specific database definition will not access the word sought and therefore contributes to the limited performance of such dictionaries.
A number of patents have issued for various "dictionaries", but careful scrutiny reveals that most of these patents are for methods or processes for checking the spelling of words in a document (U.S. Pat. Nos. 3,995,245; 4,503,514; 4,799,188; 4,833,610; and 5,297,038).
U.S. Pat. No. 5,229,936 to Decker, et al. describes a method for storage and retrieval of all forms of a word. This method is for use in electronic dictionaries, bilingual dictionaries and thesauri. The words are broken down by stem and ending sets, parts of speech and grammatical information. This system can be utilized for translating words from one language to another and to obtain grammatical information pertaining to the second language. Letkeman, in U.S. Pat. No. 5,383,121 describes a computer generated dictionary wherein words and defining phrases are reduced to numerical storage units that are compressed into a minimum of storage space. The defining phrases can be stored in several different languages so that the user can retrieve the sought after defining phrase in the desired language.
Rosenbaum, et al. (U.S. Pat. No. 4,384,329) teaches a method for finding a series of synonyms for a given word. This method defines an automatic thesaurus. The words are arranged in an N.times.N matrix wherein an "on" bit (1) corresponds to a synonym. Column positions of the "on" bit are stored. The search is performed on the first four letters of a word. A similar system can be used to retrieve antonyms, but a separate storage system and matrix are required for the antonyms.
There is a need for an electronic dictionary that can retrieve a word when one or more words which appear in its definition, or one or more words related to or synonyms for words appearing in its definition are entered. There is a need for a dictionary that anticipates the defining words that the user might enter in order to find the word sought and that therefore relies on a large database of synonyms in order to broaden search capabilities without sacrificing the speed of the search and retrieval.